potenziometrische

Potenziometrische, or potentiometric, methods are electrochemical techniques that determine an analyte by measuring the electrical potential of a cell while drawing negligible current. The measured potential reflects the activity of a specific ion or redox couple in solution and can be related to concentration through the Nernst equation. In practice, potentiometric measurements rely on a stable reference electrode and an indicator (working) electrode, often arranged in a high-impedance, two- or three-electrode setup.

The most common examples are pH measurement and ion-selective electrode (ISE) sensing. A pH measurement uses a glass or similar electrode whose potential responds to hydrogen ion activity; ISEs extend this principle to other ions such as Na+, K+, Ca2+, Cl−, and NO3−, each designed for selective response. Redox potentiometry is another variant, where the measured potential corresponds to the redox state of a system and can indicate oxidation-reduction potentials or concentrations of redox-active species.

Applications of potenziometrische techniques span analytical chemistry, environmental monitoring, clinical diagnostics, and industrial process control. Potentiometric titrations involve monitoring potential as a titrant is added, allowing the determination of equivalence points without relying on conductance or color change. Calibration against standards, electrode selectivity, and ionic strength are important for accurate results; drift and interference from competing ions are common considerations.

Advantages of potentiometric methods include simplicity, rapid response, minimal sample consumption, and broad linear ranges. Limitations include dependence on stable reference electrodes, potential interferences, the need to account for activity rather than just concentration, and calibration requirements for reliable quantitative results.